[PATCH -v3 0/8] PI vs SCHED_DEADLINE fixes

[Peter Zijlstra]

Now that this pesky little problem with futexes is (hopefully) dealt with;

  https://lkml.kernel.org/r/20170322103547.756091212@xxxxxxxxxxxxx

We can get on with fixing the actual bug this all started out with.

These patches, started by Xunlei Pang, rework the PI infrastructure a bit
fixing various problems it has, most notable a NULL deref in SCHED_DEADLINE.

Once this is sorted; we can look at improving the tracing thing (Daniel Bristot
and Julien Desfossez were working on that) and have a better foundation to look
at bandwidth inheritance (Juri and co.).